1. Technical Field
The present disclosure relates to rear conversion lens, which may include a plurality of lenses, detachably attached to an image side of a master lens, which may include a plurality of lenses, for varying the focal length of the master lens.
2. Description of the Related Art
Conversion lenses may be attached to an object side or an image side of master lenses of a photographing device, such as, for example, a camera or a video camera, for varying the focal length of the master lenses. Master lenses refer to lenses disposed in a main body of a photographing device, such as, for example, a camera or a video camera. Conversion lenses attached to an object side of master lenses are referred to as front conversion lenses, and conversion lenses attached to an image side of master lenses are referred to as rear conversion lenses.
Front conversion lenses attached to master lenses vary the focal length of the master lenses without varying brightness. However, it is difficult to decrease the overall size and aberrations of a lens system employing front conversion lenses. On the other hand, although rear conversion lenses added to a lens system vary the brightness of the lens system, it is possible to decrease the size of the lens system.
Along with the development and spread of photographing devices such as digital cameras, the use of photographing devices capable of displaying images captured using imaging devices (image sensors) on displays or electronic viewfinders has increased, and the use of photographing devices not including optical viewfinders has also increased. For example, interchangeable lens cameras have been used, and employ so called single-lens reflex finders in which light is reflected to a finder optical system by a mirror disposed at an angle of about 45 degrees with respect to an image side of photographing lenses for compatibility with various lenses. However, recent digital cameras not employing optical viewfinders are provided in the form of mirrorless cameras. Since mirrors are not used in such photographing devices, the distance between a lens mount surface and an image surface may be smaller in such photographing devices than in single-lens reflex cameras as compared to those with mirrors.